Sensors of physical signals are typically sensitive to multiple physical influences. The art of sensor design is to ensure that the sensor is the most sensitive to a physical parameter of interest. The challenge is to isolate a sensing element of one physical phenomenon from confounding physical phenomena.
For example, sensors that are placed in an environment in which varying mechanical loads may be imposed on the sensor may be subject to strain-induced errors in a physical signal measurement. It is often desirable to measure or monitor pressure within a patient's body. Blood pressure, cranial pressure or other intracavitary or internal body pressures may be monitored for assessing a patient condition and may be used in managing or controlling medical treatment. A pressure sensor implanted in a patient's body will be subjected to temperature changes as well as movement and physical forces other than pressure. For example, motion due to the beating heart, respiration or body motion may cause bending or strain of a pressure sensor module. A sensor module may be at least partially isolated from other movement and forces by positioning the pressure in or on a stiff housing that does not bend under normal operating conditions.
A housing or sensor platform that is stiff enough to prevent flexure or strain due to imposed forces on the sensor, however, may be undesirable or poorly tolerated by a patient when incorporated in an implantable medical device (IMD). For example, in a transvenous lead for monitoring blood pressure, added stiffness to the lead may make lead advancement and navigation through a tortuous pathway along the patient's cardiovascular system difficult or impossible. The stiffness of a sensor housing implemented along an otherwise flexible lead body may cause undesired strain between the housing and flexible lead body when exposed to flexure and movement associated with a beating heart or other motion. A need remains, therefore, for a pressure sensor and associated method for compensating for bending error caused by strain applied to the pressure sensor and for determining information relating to the mechanical loading of a sensor.